Measuring AD1865 DAC2

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Dear All,

I have a new measuring toy (Picotech 4424), and I am doing some measures on my gears. Main purpose is to lear how to use the instrument, understand results and put a baseline for further development.

I started measuring signals out of my MAC PRO and I measure the DAC2 designed by Quanchao.

On the latter I got some strange/interesting results. DAC has been fed both with the digital output of the laptop and with the M2Tech Iface, with no measurable difference. For the pictures I used the Iface.

Please see the images attached:
1) The first image is the FFT with no SPDIF connected. Wondering what that bomps are, but this can be not relevant
2) Second picture is a 1kHz signal 44.1 kHz. There are so many odd harmonics, but the measured THD is not so bad.
3) Third picture is the same signal with 96 kHz. The FFT looks much better, but the value of the THD is almose one order of magnitude more.
4) The last picture is a 1kHz square wave. This is where the DAC performs very well. If compared to the analog output of the MAC it is perfetc, while the MAC was showing very evident symmetric ringing.

Any comment ?

One question: for IMD I think I have to feed two signals. What are good frequencies to use ?

Additionally, I noted that the signal generator software really matters. I tries Tongen and SignalSuite. The latter is much more accurate in term of THD.

Best Regards,

Davide
 

Attachments

  • nosignalad.JPG
    nosignalad.JPG
    117.4 KB · Views: 222
  • 44ad.JPG
    44ad.JPG
    123.1 KB · Views: 223
  • 96ad.JPG
    96ad.JPG
    124.6 KB · Views: 214
  • squareadmac.JPG
    squareadmac.JPG
    53.4 KB · Views: 203
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.